The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures for implementing switching power supply controllers such as pulse width modulated (PWM) power supply controllers. The system that used the switching power supply controllers generally was configured as either a voltage boost system or a voltage buck system. Some systems were implemented as both a buck and a boost system or a buck-boost system. One example of such a buck-boost system is disclosed in U.S. Pat. No. 6,166,527 issued to Dwelley et al on Dec. 26, 2000. One problem with such a buck-boost system was that the efficiency in the buck-boost mode generally was not as high as desired. Additionally, the circuitry used to implement the buck-boost system generally was complex which resulted in a high cost.
Accordingly, it is desirable to have a switching power supply controller that can operate in a buck-boost operating mode, that has a high efficiency, that has a simpler implementation, and that has a reduced cost.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay between the reaction that is initiated by the initial action.